KR102556910B1 - Vented bearing retainer for turbomachinery - Google Patents

Abstract

Vented bearing retainers and roller bearings for turbomachinery such as compressors and turbines. An axial opening in or adjacent to the inner circumferential surface of the bearing retainer member equalizes the pressure differential on the roller bearing. An axial groove may be provided in the inner circumferential surface. A damper member on the OD of the retainer member can minimize rigid vibration modes and counteract thermal growth and misalignment.

Description

Vented bearing retainer for turbomachinery

The present invention relates to bearings for turbomachinery, and more particularly to retainers and assemblies for roller bearings.

A turbomachine transfers energy between a rotor and a fluid and includes both a turbine and a compressor. Turbines transfer energy from the fluid to the rotor (impeller), while compressors transfer energy from the rotor (impeller) to the fluid. Generally, there are open and closed turbomachines. Open machines such as propellers, windmills, and open fans operate with an infinite amount of fluid, whereas closed machines operate with a finite amount of fluid as it passes through a housing or casing. Turbomachines are also classified according to whether they are axial flow machines or radial (centrifugal) flow machines.

Compressor turbomachines and turbine turbomachines typically include a rotating shaft disposed within a body or housing with an impeller at one end. Rotation of the shaft causes rotation of the impeller, which in turn compresses or facilitates the flow of the fluid. Bearings, such as roller bearings, are provided to enable the shaft to rotate freely.

Correct lubrication is critical to bearing performance and life. In the case of permanently lubricated bearings, it is also necessary to equalize the pressure differentials to extrude the lubricant out of the bearing. Retainer members not only help prevent loss of lubricating oil from the bearings, but can also be used to prevent contaminants from entering the bearings and degrading their performance and durability.

In the case of high-speed turbomachines, it is also important to prevent the outer race of the roller bearings or gear retainers from rotating at the same speed as the shaft and impeller, thereby increasing their duration and performance.

Accordingly, an object of the present invention is an improved retaining member for a permanently lubricated bearing, and a permanently lubricated bearing and an improved retaining member, in which not only the retention of lubricant is improved, but also the durability and life of the assembly are improved. to provide an assembly of Another object of the present invention is to provide an improved roller bearing and retainer assembly, as well as an improved retainer member for roller bearings.

These and other objects are met by the present invention, which provides improved bearing retainer members and improved combinations of such retainer members with bearings, such as roller bearings. The bearing retainer member has one or more axial vents adjacent its inner circumferential surface. The vent equalizes the pressure differential to extrude the lubricating oil from the bearing, for example to the lower bearing side shield. Additionally, one or more radial grooves may be provided on the inner circumferential surface of the retainer member adjacent the axial vent. The radial grooves provide a bypass for gases that may develop near the roller bearings or assemblies.

To provide damping and limit rotation of the bearing retainer member within the housing, one or more damping members are provided on an outer circumferential surface of the retainer member. The damping member may be a rubber or elastomeric ring member, such as an O-ring, or may be a metal compressible structural member that provides damping and frictional contact with the housing.

Other features of the present invention, as well as other advantages and advantages, will become apparent from the following description of the invention in combination with the accompanying drawings and appended claims.

1 is a cross-sectional perspective view of a representative turbomachine using the present invention.
FIG. 2 is an exploded view of area 2 of FIG. 1 .
3 is a perspective view of a combination of a roller bearing and a bearing holding member according to the present invention.
Figure 4 is a cross-sectional view of the present invention shown in Figure 3;
5 is a perspective view of a bearing retainer member according to the present invention.
Figure 6 is an exploded view of the present invention shown in Figures 3 and 4;
7 shows an alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates in particular to a permanently lubricated roller bearing mechanism for high-speed turbomachines such as turbine generators or electric superchargers, and will be described herein in an exemplary manner. However, the present invention should not be limited to using the present invention only for these situations and for these products. Turbomachinery can support a variety of impellers, including turbines, compressors, pumps, fans, etc. The bearing may also be any type of standard bearing, such as various types of ball bearings or roller bearings such as cylindrical roller bearings, tapered roller bearings, spherical roller bearings, and the like. The roller elements may also be arranged in one or more rows. The type of grease or lubricating oil used may also be of any standard type or may be newly synthesized in the future.

The bearings also need not be of the permanently lubricated type. It may be a bearing with a port for replenishment of lubricating oil. The grease or lubricant should preferably be of a type and amount sufficient to seal the bearing mechanism against moisture as well as solid and liquid contaminants. The amount of grease applied to the bearing usually depends on the application. Insufficient amounts of grease can cause metal-to-metal contact and premature bearing failure. Excessive amounts of grease can rapidly increase the operating temperature within the bearing. The amount of grease may also depend on the speed range of the bearing. Higher quantities of lubricant (up to 100% charged) are typically used for low speed applications, and smaller quantities of lubricant (eg, 30-50%) are typically used for medium to high speed applications.

Retainer members such as end caps or end shields are also used to retain grease within the bearing and provide longer bearing life. Grease may be applied to the retainer or cap member, and then the roller bearing may be assembled in or with the retainer member capturing as much grease as possible in the bearing-retainer assembly.

Additionally, although the use of a damping or softening member such as an O-ring or metal biasing member is preferred, such an item may not be necessary in certain embodiments of the retainer and bearing assembly. Soft mounting assemblies are desirable because they can reduce or prevent rotation of the retainer member, enable axial movement, ensure effective axial preload, and also lower rigid vibration modes of the rotating assembly. Soft mount assemblies can also better cope with thermal growth and misalignment.

Referring to FIG. 1 , the present invention used in a representative turbine generator 10 is shown. The turbine includes a housing 15, a rotating shaft member 14 mounted therein, a fluid duct 17, and an impeller 16 attached to one end of the shaft member.

Shaft member 14 is rotatably mounted within stator housing 12 by a pair of bearing assemblies 18, 20. An electric motor 22 in the stator housing is used to generate power to rotate the shaft member. The motor has a stator member 24 that rotates a rotor member 26 fixedly attached to the shaft member 14 . The turbomachine (10) also has a labyrinth seal (23), a heat shield (25), and a cooling water passage (27).

Bearing assemblies 18 and 20 may all be of the same type of bearing, or may be of different types. A bearing assembly 20 will be described herein in terms of use of the preferred embodiment of the present invention. The bearing 18 is preferably of the same type and has the same components as the vented bearing assembly 20 .

A bearing assembly 20 of the present invention is shown in FIGS. 2-6. Assembly 20 generally includes a bearing member 25 and a retainer member 30 . In the embodiment shown, the bearing member is a roller bearing having a plurality of spherical ball members 32 disposed within a cage member 38 . Although seven ball members 32 are shown, the number of ball members is not critical and can be any number used in roller bearings of this type.

The roller bearing assembly 20 includes an inner race member 34 and an outer race member 36, both of which have curved raceways 35 and 37 to the ball members, respectively. A ball holder member 36, also referred to as a “cage,” is positioned between the two race members and is used to hold the ball members in place and space them evenly around the circumference of the bearing assembly. One of the ball members 32 is disposed within each opening 39 in the cage member 38.

Annular shield members 40, 42 are disposed on the two axial sides of the two race members. Retainer members 40, 42 help retain lubricant within the roller bearing members so that the bearings operate satisfactorily.

The cap type retainer member 30 is best seen in FIGS. 3-6. The retainer member 30 has an outer (OD) circumferential surface 50 and an inner (ID) circumferential surface 52 . Retainer member 30 also has a radial annular flange member 54 .

Preferably, the retainer member 30 is made of a metal material having suitable strength, thermal, magnetic and fabrication properties such as steel or aluminum material. Likewise, inner race member 34 and outer race member 36 are made of similar materials. The ball member 32 is preferably made of silicon nitride or any suitable material. Metal ball materials such as steel may be of limited use for high speed electric turbomachines because of their high centrifugal force, thermal expansion and electrical conductivity. The holder member 38 is preferably made of a plastic or polymeric material.

A plurality of axial vent openings 60 are provided in retainer member 30 . A vent opening is provided adjacent the inner circumferential surface 52 of the retainer member 30, as shown more specifically in FIGS. 5 and 6 . Vent openings are provided to equalize any pressure differential that would force lubricating oil past the side shields 40, 42 and out of the bearing member.

Preferably, three vent openings 60 are provided, but there may be fewer or more. The vent openings are also preferably evenly spaced on the retainer member as shown in Figures 3-6. Evenly spacing the vent openings can avoid distortion of the outer race. The size of the vent is not critical as long as a suitable pressure differential equalizes it.

A plurality of grooves 70 are provided on the inner circumferential surface 52 of the retainer member 30 . The grooves are preferably oriented in the axial direction. The depth of the groove may be, for example, 10% to 80% of the thickness of the retainer member. Grooves are provided to allow any gases formed in the turbine housing around the shaft member or caused by the bearing assembly 20 to be bypassed and vented through the vent opening 60 . Although three grooves 70 are shown in the figure, the actual number may be greater than or less than three. Preferably the number is the same as the number of vent openings for efficient removal of gas and equalization of any pressure differential, preferably the grooves 70 are aligned with and communicate with the vent openings 60 as shown.

The radial bypass flow of gas from the bearing ID to the outer race of the bearing is indicated by arrow 74 in FIG. 4 . Axial groove 70 provides a bypass flow path on the inner circumferential surface in the manner indicated by arrow 76 in FIG. 4 .

Preferably, the vent opening 60 and the groove 70 are formed simultaneously and in the same single machining or comminution milling procedure. Vent openings and grooves may also be formed by any other conventional forming operation, such as casting, sintering, metal injection molding, 3D printing, and the like. They can also be formed from one axial side of the retainer member in one step. The geometries of the vent openings and grooves shown in the drawings are provided to be achieved in this manner. This reduces the cost and time required to manufacture the retainer member 30 as well as the complete bearing assembly 20.

An embodiment of the present invention in which the vent opening 60 and groove 70 can be formed in one step machining operation is shown in FIGS. 5 and 6 .

Vent openings through the flange wall 54 prevent bearing pressure differentials during high speed, high boost operation. Direct bearing vents 60 also ensure equalized pressure under all conditions.

In addition to vent openings and grooves, preferred bearing assemblies also have damping "soft" mounting features. In one embodiment, one or more O-ring grooves 80 are located on the outer (OD) circumferential surface 50 of the retainer member 30 . O-ring member 82, as best seen in FIG. 4, is located within groove 80 and extends slightly above surface 50. A "soft" mounting of the bearing assembly 20 within the turbine housing 12 is shown in FIGS. 1 and 2 .

When the roller bearing and retainer member assembly is installed in the housing, the O-ring provides a flexible mounting for the assembly in the turbomachine. Soft mounting provides structural damping, slowing down the rate at which rigid modes of motion and vibration are encountered. "Soft" mounting also counteracts any thermal growth and/or misalignment of the bearing assembly within the housing. The O-ring also provides friction with the housing and limits the rotational speed of the retainer member relative to the speed of the shaft member and roller bearing.

O-ring 82 may be a suitable chemical and heat-resistant elastomeric O-ring of any conventional type in use today. An O-ring located within the outer surface of the retainer member provides a floating mount for the bearing assembly 20 within the compressor housing 12.

An alternative embodiment 100 of the bearing assembly of the present invention is shown in FIG. 7 . This embodiment 100 includes the same vent openings 60 and radial grooves 70 as the previously described embodiment 10, but with different damping features. Rather than using one or two O-rings in the circumferential groove, embodiment 100 instead includes a metal structure damper member 102 on the outer circumferential surface 104 of the retainer member. The damper member 102 is preferably located in a circumferential groove 106 on the outer surface 104 . The metal damper member has, around its circumference, a plurality of flexible parts or flexible members 108 that provide a biasing force on the housing. When the bearing assembly 100 is mounted or assembled to the housing, the biasing member 108 holds the bearing assembly in place and provides the same “soft” fit described above with respect to FIGS. 1-6. Preferably, the metal damper member 102 includes an anti-rotation feature such as member 120 to prevent the damper member from rotating. The bearing assembly is also capable of sliding axially on the shaft member and preferably provides a radial damping force.

While the invention has been described in connection with one or more embodiments, the specific mechanisms and techniques described are merely illustrative of the principles of the invention, and the spirit and scope of the invention as defined by the appended claims. It is to be understood that various modifications may be made to the described methods and apparatus without departing from them.

Claims (15)

A bearing retainer member for use with roller bearings, the bearing retainer member comprising:
A circular axially extending annular wall member having an outer surface and an inner surface, and a radially extending wall flange member attached to the annular wall member, comprising:
said wall flange member having at least one vent opening for the passage of gas, and
and at least one groove communicating with each other in axial alignment with the at least one vent opening on the inner surface of the circular axially extending annular wall member. 2. The bearing retainer member of claim 1, wherein a plurality of vent openings are provided in the wall flange member. The bearing retainer member according to claim 1, wherein a plurality of grooves are provided in the inner surface of the circular axially extending wall member. The bearing retainer member according to claim 1, wherein the vent opening and the groove can be simultaneously formed in a single machining operation. The bearing retainer member according to claim 1, further comprising at least one O-ring groove provided in a circumferential direction on the outer surface. A roller bearing assembly comprising a roller bearing mechanism and a bearing retainer member, the roller bearing mechanism comprising an inner race member, an outer race member and a plurality of roller members positioned between the inner and outer race members, the bearing retainer member comprising: A circular axially extending annular wall member having outer and inner surfaces, and a radially extending wall flange member attached to the annular wall member, the wall flange having at least one vent opening for the passage of gas. member, and at least one groove axially aligned with and communicating with the at least one vent opening on the inner surface of the circular axially extending annular wall member, the roller bearing mechanism comprising: the bearing retainer member; wherein a pressure differential between axial sides of the wall flange member can be equalized. 7. The roller bearing assembly of claim 6, wherein a plurality of vent openings are provided in the wall flange member. 7. The roller bearing assembly according to claim 6, wherein a plurality of grooves are provided in the inner surface of the circular axially extending wall member. 7. The roller bearing assembly of claim 6, wherein the vent opening and the groove can be simultaneously formed in a single machining operation. 7. The roller bearing assembly of claim 6, further comprising at least one O-ring groove provided circumferentially on the outer surface, and an O-ring positioned within the groove. 7. The roller bearing assembly of claim 6, further comprising a turbomachine having a housing member, wherein at least one roller bearing assembly is positioned within the housing member. As a turbomachine for internal combustion engines:
housing;
an impeller member disposed within the housing;
a shaft to which the impeller member is coupled and extending through the housing; and
a bearing assembly coupled to the shaft and the housing and having a retainer member;
The retainer member has an axially extending annular wall member and a radially extending wall flange member attached to the annular wall member, the wall flange member having at least one vent opening for passage of gas so as to Turbomachinery, balancing the pressure on each side of the bearing assembly. 13. The method of claim 12, wherein the bearing assembly includes the retainer member and a roller-element bearing received therein, the retainer member coupled to the housing, an annular damping member radially compressed therebetween, the retainer member The member includes at least one radially extending passage that passes radially inward toward the roller-element bearing to balance pressure across both sides of the roller-element bearing. 14. The turbomachine according to claim 13, wherein the annular damping member is at least one O-ring member or metal structure damper member. 14. The turbomachine according to claim 13, wherein the turbomachine is a turbine or compressor turbomachine.

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